From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-72101][MODERATE REGULAR] dm-integrity: fix leaking uninitialized kernel memory [ Upstream Date: Sun, 16 Aug 2026 08:47:58 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-72101 X-AL-KERNEL-Priority: MODERATE REGULAR X-AL-KERNEL-Severity: MODERATE REGULAR X-AL-KERNEL-Base-Severity: MODERATE X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 3 X-AL-KERNEL-ActionableScore-Lower: 1 X-AL-KERNEL-Commit: 50af3e51dc709384701dbc721b4bd865285c5f2c List-Id: CVE: CVE-2026-72101 Priority: MODERATE REGULAR AL-KERNEL base severity: MODERATE KPANIC flag: NO Patch: dm-integrity: fix leaking uninitialized kernel memory [ Upstream Commit: 50af3e51dc709384701dbc721b4bd865285c5f2c Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=50af3e51dc709384701dbc721b4bd865285c5f2c Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101 Analysis date: Sun, 16 Aug 2026 08:47:58 -0400 ActionableScore: 3 ActionableScore lower bound: 1 Actionable bucket: Borderline manual review recommended Manual review required: YES Summary: dm-integrity inline mode may leak uninitialized kernel memory because padding between tag_size and tuple_size was not zeroed before integrity metadata was used or stored. ====================================================================== ABOUT THIS REPORT ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72101 is available here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101 The original announcement does not normally provide a security severity estimate, CVSS assessment, or enough information to determine whether the reported kernel bug represents a practically relevant security issue. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. It combines an autonomous classifier with LLM-assisted technical analysis and a separate ActionableScore mechanism. The purpose of this report is to prioritize Linux kernel CVEs before manual review, identify cases that require prompt investigation, and support automatic closure of issues that are unlikely to have meaningful security impact. Published priority for this report: MODERATE REGULAR Manual review required: YES A detailed explanation of the methodology and priority rules is included at the end of this message. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== CVE-2026-72101 MODERATE CHECK WITH IMPACT FROM ORIG NN LOW Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N';CWE-908;*CWE-200;CWE-665;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N';BEST CVSS score: '5.5';DESCR 'dm-integrity inline mode can leak uninitialized kernel memory because the padding area between tag_size and tuple_size is not actually zeroed. The memset length is computed as tuple_size minus tuple_size, so no bytes are cleared before the integrity payload is used. For the CVSS the PR:L is used in the paranoid score if a local user or service can trigger I/O on the dm-integrity device and later read the affected metadata or device image. The issue is not network reachable and requires local access to a system using dm-integrity inline mode. Impact is information disclosure only, with no evidence of memory corruption, privilege escalation, or denial of service.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline manual review recommended (with actual score 2) YES DISK SIMPLEFIX LEAK HARDWARE LINUS INCREASED_FROM_LOW_BASED_ON_REQUIREMANUALCHECK DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 YES NO checked ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== ActionableScore=3 ActionableScoreLower=1 ## 1. ActionableScore * Conservative score: 1 * Paranoid score: 3 * Final recommended bucket: **Borderline manual review recommended**:: ## 2. Signal breakdown Conservative signals: * Confidentiality impact plausible: +1. The bug is explicitly an uninitialized kernel memory disclosure in dm-integrity inline metadata. * Important filesystem/storage path: +1. The affected code is in device-mapper integrity handling. * Rare or configuration-dependent mode: -1. The issue requires dm-integrity inline mode with tag_size smaller than tuple_size. Paranoid additional signal: * Local unprivileged trigger: +1. If a local user or service can generate I/O on an affected dm-integrity-backed device and later access the exposed integrity metadata, practical leakage may be possible. Not awarded: * No generic memory corruption. The patch fixes a zero-length memset and does not show OOB write, UAF, double free, or type confusion. * No privilege escalation signal. The primitive is information disclosure only. * No remote reachability. This is a local storage stack issue. * No DoS signal. The patch does not indicate crash, hang, or filesystem shutdown. ## 3. Reachability analysis The bug is reachable only on systems using dm-integrity inline mode where tag_size is smaller than tuple_size. Triggering the affected path requires I/O through the dm-integrity device. Practical exploitation depends on whether the leaked integrity payload bytes are observable by the attacker, for example through raw block access, backup images, lower-layer device access, or delegated storage access. In typical deployments, creating or inspecting dm-integrity metadata is administrative, but a less privileged local user may still be able to trigger I/O through a filesystem placed on top of the device. ## 4. Severity interpretation This behaves like an information disclosure issue, not memory corruption. The theoretical impact is kernel memory disclosure from uninitialized bytes in the integrity tuple padding. Realistic severity depends heavily on whether an attacker can read the affected metadata or backing storage. It is not an Important-class candidate by itself, but it should not be blindly auto-closed without checking deployment exposure. ## 5. One-sentence report phrase dm-integrity inline mode may leak uninitialized kernel memory because padding between tag_size and tuple_size was not zeroed before integrity metadata was used or stored. ## 6. Manual review recommendation MANUAL CHECK RECOMMENDED. Review should confirm whether affected systems use dm-integrity inline mode and whether non-admin users or services can observe the integrity metadata or underlying storage image. ====================================================================== UPSTREAM PATCH SUMMARY ====================================================================== Patch: dm-integrity: fix leaking uninitialized kernel memory [ Upstream Commit: 50af3e51dc709384701dbc721b4bd865285c5f2c Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=50af3e51dc709384701dbc721b4bd865285c5f2c Changed files: drivers/md/dm-integrity.c Diff excerpt: Not included in this email. See the upstream URL for the full patch. Full patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=50af3e51dc709384701dbc721b4bd865285c5f2c ====================================================================== DETAILED REPORT METHODOLOGY ====================================================================== The original Linux kernel CVE announcement for CVE-2026-72101 can be found here: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72101 The original CVE announcement normally does not include a security-level estimate. In particular, it may not contain a CVSS assessment, an impact level, or enough information to determine whether the reported bug is a practically relevant security issue. One purpose of this parallel CVE list is to provide that missing technical and prioritization information. The original goal of the AL-KERNEL project was to prioritize Linux kernel CVE analysis automatically before manual review. The system can also help identify non-security issues that may be suitable for automatic closure. This report was generated by AL-KERNEL, an AI-assisted Linux kernel vulnerability analysis system developed by Alexander Larkin. The first analysis stage combines an autonomous classifier with additional LLM-based analysis. The autonomous classifier runs locally on a CPU and is based on a backpropagation neural network. Together, these mechanisms produce a technical vulnerability description, identify likely weakness types, estimate CVSS severity, and provide input for ActionableScore. Two CVSS estimates are retained because incomplete kernel vulnerability information often permits more than one defensible interpretation: Conservative CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N The Best / paranoid CVSS score: 5.5 The conservative vector represents a lower-impact interpretation. The Best/paranoid vector intentionally represents a plausible upper-bound interpretation and should not automatically be treated as demonstrated real-world impact. CVSS may also need to be adjusted for a particular Linux deployment, because actual reachability, privileges, enabled kernel configuration, hardware, namespaces, exposed device nodes, and other environmental conditions can differ significantly between systems. A separate ActionableScore mechanism evaluates practical remediation urgency. Its analysis may include reachability, attack prerequisites, subsystem exposure, memory-corruption characteristics, denial-of-service reliability, and possible confidentiality, integrity, or privilege-escalation impact. Conservative ActionableScore: 1 Paranoid ActionableScore: 3 The final base severity is taken directly from the second tab-separated field of the AL-KERNEL classification result. ActionableScore does not replace or independently override that final AL-KERNEL decision, and if ActionableScore adjusted impact level of ALKERNEL, then you would see self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7. For an AL-KERNEL result of MODERATE, this report uses the following additional presentation split: ActionableScore below 5 -> MODERATE REGULAR ActionableScore 5 or more -> MODERATE 7.0 The distinction between MODERATE REGULAR and MODERATE 7.0 makes it possible to identify Moderate issues that should receive manual analysis and fixes before lower-priority MODERATE REGULAR issues. In many cases, MODERATE REGULAR fixes may wait for a later rebase or routine update. There is one override in which MODERATE REGULAR becomes MODERATE 7.0 even when the ActionableScore is below 5. When the AL-KERNEL result contains the KPANIC flag, a MODERATE result is always presented as MODERATE 7.0. The KPANIC flag selected with few regexps without usage of AI at all, so it helps to detect cases when Kernel Crash happens and similar (to filter False-Negative results from the LLM usage). KPANIC indicates that a reliable kernel crash, kernel panic, or similarly serious kernel availability impact was identified by the classification workflow. AL-KERNEL base severity for this report: MODERATE KPANIC detected for this report: NO Published priority for this report (same as in Subject): MODERATE REGULAR These results are intended to support engineering triage. They are machine-generated estimates, and cases marked for manual review should be validated by a human security engineer before final disposition. For more info read docs linked from here: https://kernelcve.org/ (and you can submit you own patch there to generate such a report for non-existant CVE-id yet). Note that in many cases this AI tool selects higher severity, than real is (means you can expect Importants instead of Moderate 7.0 or Moderates 7.0 instead of regular Moderates). If you see such cases, please use reply email interface to add additional manual analyses info to this particular CVE. And please, please, let me know when you see Lows instead of Importants or Important instead of Low (because particular for such cases I need to tune this AI tool to make it better for this one and next similar). My contact email for such notifications is alexanjelausa@gmail.com (and both send reply to CVE record itself too and see "reply" button below for howto reply).